The present invention relates to cochlear implants, and more particularly to a bionic ear programming system that may be used with the more sophisticated and complex cochlear implants that are now available.
Electrical stimulation of predetermined locations within the cochlea of the human ear through an intra-cochlear electrode array is described, e.g., in U.S. Pat. No. 4,400,590. The electrode array shown in the '590 patent comprises a plurality of exposed electrode pairs spaced along and imbedded in a resilient curved base for implantation in accordance with a method of surgical implantation, e.g., as described in U.S. Pat. No. 3,751,615. The system described in the '590 patent receives audio signals, i.e., sound waves, at a signal processor (or speech processor) located outside the body of a hearing impaired patient. The speech processor converts the received audio signals into modulated RF data signals that are transmitted by a cable connection through the patient's skin to an implanted multi-channel intracochlear electrode array. The modulated RF signals are demodulated into analog signals and are applied to selected ones of the plurality of exposed electrode pairs in the intra-cochlear electrode so as to electrically stimulate predetermined locations of the auditory nerve within the cochlea.
A new, more sophisticated, class of cochlear implant, referred to as a bionic ear, is now available to provide patients with enhanced hearing performance. For example, Advanced Bionics Corporation, of Sylmar Calif., currently offers a cochlear implant which it refers to as the CII Bionic Ear™ cochlear implant. Many features associated with the CII Bionic Ear implant are described in U.S. Pat. No. 6,219,580, incorporated herein by reference. Advantageously, with the CII Bionic Ear™ cochlear implant, more than twice as much sound can be captured, and 10 times more processing power is available to process such sound. Further, the CII Bionic Ear implant contains internal memory banks that enable it to send very detailed, high resolution sound signals to the auditory nerve. Such signals are delivered to the auditory nerve using a special electrode adapted to be inserted into the cochlea. A representative electrode usable with the CII Bionic ear is described in U.S. Pat. No. 6,129,753, also incorporated herein by reference.
Other improved features of cochlear implant systems are taught, e.g., in U.S. Pat. Nos. 5,626,629; 6,067,474; 6,157,861; 6,219,580; 6,249,704; and 6,289,247, each of which patents is incorporated herein by reference.
Advantageously, the implantable cochlear stimulators described in the '629, '474, '861, '580 and '704 patents are able to selectively control the pulse width of stimulating pulses that are applied through the electrode array to the cochlea, and the frequency at which the stimulating pulses are applied.
As the art of cochlear stimulation has advanced, the implanted portion of the cochlear stimulation system, and the externally wearable processor (or speech processor), if used (much of the circuitry previously employed in the externally wearable processor has been moved to the implanted portion, thereby reducing the amount of information that must be transmitted from the external wearable processor to the implanted portion), have become increasingly complicated and sophisticated. The amount of control and discretion exercisable by an audiologist in selecting the modes and methods of operation of the cochlear stimulation system have increased dramatically and it is no longer possible to fully control and customize the operation of the cochlear stimulation system through the use of, for example, switches located on the speech processor. As a result, it has become necessary to utilize an implantable cochlear stimulator fitting system to establish the operating modes and methods of the cochlear stimulation system and then to download such programming into the speech processor. One such fitting system is described in the '629 patent. An improved fitting system is described in the '247 patent. The present invention is directed to a still further improved fitting system that may be used with a bionic ear cochlear implant.
The '247 patent further highlights representative stimulation strategies that may be employed by a multichannel stimulation system. Such strategies represent the manner or technique in which the stimulation current is applied to the electrodes of an electrode array used with the stimulation system. Such stimulation strategies, all of which apply current pulses to selected electrodes, may be broadly classified as: (1) sequential or non-simultaneous (where only one electrode receives a current pulse at the same time); (2) simultaneous (where substantially all of the electrodes receive current stimuli at the same time, thereby approximating an analog signal); or (3) partially simultaneous pulsitile stimulation (where only a select grouping of the electrodes receive stimuli at the same time in accordance with a predefined pattern).
Typically, when the fitting systems described in the '629 or '247 patents are employed for multichannel stimulation systems, or when equivalent or similar fitting systems are employed, it is necessary to use directly measured threshold values and/or thresholds derived from the measurement of phsycophysically-determined psuedo-comfort levels. That is, for each channel of the multichannel system, a minimum threshold level is measured, typically referred to as a “T” level, which represents the minium stimulation current which when applied to a given electrode associated with the channel produces a sensed perception of sound at least 50% of the time. In a similar manner, an “M” level is determined for each channel, which represents a stimulation current which when applied to the given electrode produces a sensed perception of sound that is moderately loud, or comfortably loud, but not so loud that the perceived sound is uncomfortable. These “T” and “M” levels are then used by the fitting software in order to properly map sensed sound to stimulation current levels that can be perceived by the patient as sound.
Disadvantageously, determining the “T” and/or “M” levels (or other required thresholds) associated with each channel of a multichannel stimulation system is an extremely laborious and time-intensive task. Such determinations require significant time commitments on the part of the clinician, as well as the patient. Moreover, once determined one channel at a time, such levels may not be representative of actual threshold levels that are present during real speech.